More facts about multiple sclerosis

MS symptoms

Symptoms of multiple sclerosis are unpredictable. They can vary from person to person and from time to time, in the same person.

For example, one person may experience abnormal fatigue and episodes of numbness and tingling. Another could have loss of balance and muscle coordination, making walking difficult. Weakness could also be a problem. Yet another person might have slurred speech, tremors, stiffness or vision and/or bladder problems.

Sometimes major symptoms disappear completely, and the person regains lost function. In severe MS, people have permanent symptoms that might include partial or complete paralysis and difficulties with vision, cognition, speech and elimination.

What causes MS symptoms?

MS symptoms result when an immune system attack affects myelin, the protective insulation surrounding nerve fibers of the central nervous system. Myelin is often compared to the insulating material around an electrical wire; loss of myelin interferes with transmission of nerve signals. Myelin is destroyed and replaced by scars of hardened sclerotic tissue. The damage appears in multiple places within the central nervous system, hence the name multiple sclerosis. Some underlying nerve fibers are permanently damaged or severed as well.

What are the different types of MS?

In an effort to develop a common language for evaluating and researching MS, an international survey was conducted among scientists who specialize in MS research and patient care. Analysis of responses resulted in defining the following four categories, which were introduced in 1996.

1. Relapsing-remitting: People with this type of MS experience clearly defined flare-ups, also called relapses, attacks or exacerbations. These are episodes of acute worsening of neurologic function. They are followed by partial or complete recovery periods (remissions) that are free of disease progression.

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This is the most common form of MS at the time of initial diagnosis. Approximately 85 percent of those with MS have this type.

2. Primary-progressive: People with this type of MS experience a slow but nearly continuous worsening of their disease from the onset, with no distinct relapses or remissions. However, there are variations in rates of progression over time, occasional plateaus and temporary minor improvements.

This type of MS is relatively rare. Approximately 10 percent of those with MS have this type.

3. Secondary-progressive: People with this type of MS experience an initial period relapsing-remitting MS, followed by a steadily worsening disease course with or without occasional flare-ups, minor recoveries (remissions) or plateaus.

According to studies in people who were not using disease-modifying MS therapies, approximately half if those whose MS begins with a relapsing-remitting course transition to this form of MS within 10 to 20 years of their initial diagnosis. Long-term data are not yet available to determine if this transition to secondary-progressive MS is significantly delayed by the available disease-modifying therapies.

4. Progressive-remitting: People with this type of MS experience a steadily worsening disease from the onset but subsequently have clear acute relapses (attacks or exacerbations), with or without recovery. In contrast to relapsing-remitting MS, the periods between relapses are characterized by continuing disease progression.

This type of MS is relatively rare. Approximately 5 percent of those with MS have this type.

Upcoming columns will address commonly asked questions about MS, what can be done now and what the future holds.

Anne MacMurray is retired from a more than 30-year career supporting biomedical research. Since 1995 she has been an MS patient advocate for the National Multiple Sclerosis Society. She was diagnosed with MS in 1993.